AGGRCOW - Aggressive cows


Farmer John has built a new long barn, with N (2 <= N <= 100,000) stalls. The stalls are located along a straight line at positions x1,...,xN (0 <= xi <= 1,000,000,000).

His C (2 <= C <= N) cows don't like this barn layout and become aggressive towards each other once put into a stall. To prevent the cows from hurting each other, FJ wants to assign the cows to the stalls, such that the minimum distance between any two of them is as large as possible. What is the largest minimum distance?

Input

t – the number of test cases, then t test cases follows.
* Line 1: Two space-separated integers: N and C
* Lines 2..N+1: Line i+1 contains an integer stall location, xi

Output

For each test case output one integer: the largest minimum distance.

Example

Input:

1
5 3
1
2
8
4
9

Output:

3

Output details:

FJ can put his 3 cows in the stalls at positions 1, 4 and 8,
resulting in a minimum distance of 3.


hide comments
arun m dabbe: 2020-02-15 08:43:29

Very interesting problem , classic .

sayan_244: 2020-01-30 15:46:11

>.> You need to be bit lucky for the greedy approach to strike. Took me a whole day.

And rare for me but AC in a single go :p
P.S :-Read Topcoder as suggested by many. Its not just greedy alone but coupled with Binary Search

Last edit: 2020-01-30 15:50:43
abhi1999: 2020-01-23 15:20:28

Where can i find solution of the problem

transonviet: 2020-01-02 05:32:50

AC in one go

heromayank2: 2019-12-24 15:20:19

Poor Explanation

hellb0y_suru: 2019-12-17 20:39:46

AC in one go !!!
good question on BinarySearch !!!
must do !!

saurav_03: 2019-12-08 10:10:49

interesting problem

saurav_23: 2019-10-26 08:52:01

AC in one go! Good question but sample test case could've been better.

gadela_kesav4: 2019-10-17 18:34:03

Test cases are not up to mark showing correct answer even if coded wrong

dhairya_2000: 2019-09-29 13:22:29

Finally One Correct in One Go!!


Added by:Roman Sol
Date:2005-02-16
Time limit:2s
Source limit:10000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All
Resource:USACO February 2005 Gold Division